Individuals with dysvascular amputation often undergo additional, higher-level amputations due to a progression of the underlying disease. It can be calculated that nearly $2.0 billion is spent each year in the United States on costs related to reamputation of dysvascular residual limbs that had undergone a previously healed amputation. In addition to the substantial financial costs, data shows a negative impact on numerous psychosocial and functional variables are associated with higher level amputations. Ulceration has been identified as a component in 85% of amputation cases and is the most common precursor to lower limb amputation. Ulcers develop when the metabolic demands of the cutaneous tissues cannot be met by the circulatory system. In addition, healing of ulcers requires adequate tissue perfusion. Intermittent compression (IC) of the dysvascular limb has been shown to increase blood flow to the extremities and drastically improve limb salvage rates. However, the effectiveness of the device is directly related to patient compliance. Current commercially available IC devices could be improved upon to increase patient compliance and maximize the effectiveness of IC therapy. LTI has previously developed an intermittent compression actuator that has several improvements over existing IC devices. The primary focus of this proposal is to explore both the safety and efficacy of the prototype actuator. This will be accomplished by creating improved instrumented residual limb models that mimic the shape, mechanical properties and underlying skeletal structure of residual limbs. The limb models will be instrumented so that they will be able to record both normal and shear forces applied to the limb model at multiple locations. This instrumented limb model will then be used to compare an existing pneumatic IC devices to the prototype actuator to determine how consistently each device produces pressure around the circumference of the limb. The model will also be used to determine if the prototype actuator creates shear loads on the residual limb that are within an acceptable range to not cause tissue damage. In addition, methods will be developed to integrate the actuator into a prosthetic socket and protect the limb by reducing friction between the skin and the actuator to ensure good skin health. Finally, a pilot human subjects study will be conducted to quantify the changes in tissue oxygenation created by the prototype actuation system to confirm its efficacy.